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Joe Fernandez
88 lines
3.9 KiB
Markdown
88 lines
3.9 KiB
Markdown
# Introduction to Conversational Context: Session, State, and Memory
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<div class="language-support-tag">
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<span class="lst-supported">Supported in ADK</span><span class="lst-python">Python</span><span class="lst-go">Go</span><span class="lst-java">Java</span>
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</div>
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Meaningful, multi-turn conversations require agents to understand context. Just
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like humans, they need to recall the conversation history: what's been said and
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done to maintain continuity and avoid repetition. The Agent Development Kit
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(ADK) provides structured ways to manage this context through `Session`,
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`State`, and `Memory`.
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## Core Concepts
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Think of different instances of your conversations with the agent as distinct
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**conversation threads**, potentially drawing upon **long-term knowledge**.
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1. **`Session`**: The Current Conversation Thread
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* Represents a *single, ongoing interaction* between a user and your agent
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system.
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* Contains the chronological sequence of messages and actions taken by the
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agent (referred to `Events`) during *that specific interaction*.
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* A `Session` can also hold temporary data (`State`) relevant only *during
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this conversation*.
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2. **`State` (`session.state`)**: Data Within the Current Conversation
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* Data stored within a specific `Session`.
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* Used to manage information relevant *only* to the *current, active*
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conversation thread (e.g., items in a shopping cart *during this chat*,
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user preferences mentioned *in this session*).
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3. **`Memory`**: Searchable, Cross-Session Information
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* Represents a store of information that might span *multiple past
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sessions* or include external data sources.
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* It acts as a knowledge base the agent can *search* to recall information
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or context beyond the immediate conversation.
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## Managing Context: Services
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ADK provides services to manage these concepts:
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1. **`SessionService`**: Manages the different conversation threads (`Session`
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objects)
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* Handles the lifecycle: creating, retrieving, updating (appending
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`Events`, modifying `State`), and deleting individual `Session`s.
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2. **`MemoryService`**: Manages the Long-Term Knowledge Store (`Memory`)
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* Handles ingesting information (often from completed `Session`s) into the
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long-term store.
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* Provides methods to search this stored knowledge based on queries.
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**Implementations**: ADK offers different implementations for both
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`SessionService` and `MemoryService`, allowing you to choose the storage backend
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that best fits your application's needs. Notably, **in-memory implementations**
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are provided for both services; these are designed specifically for **local
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testing and fast development**. It's important to remember that **all data
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stored using these in-memory options (sessions, state, or long-term knowledge)
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is lost when your application restarts**. For persistence and scalability beyond
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local testing, ADK also offers cloud-based and database service options.
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**In Summary:**
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* **`Session` & `State`**: Focus on the **current interaction** – the history
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and data of the *single, active conversation*. Managed primarily by a
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`SessionService`.
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* **Memory**: Focuses on the **past and external information** – a *searchable
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archive* potentially spanning across conversations. Managed by a
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`MemoryService`.
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## What's Next?
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In the following sections, we'll dive deeper into each of these components:
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* **`Session`**: Understanding its structure and `Events`.
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* **`State`**: How to effectively read, write, and manage session-specific
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data.
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* **`SessionService`**: Choosing the right storage backend for your sessions.
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* **`MemoryService`**: Exploring options for storing and retrieving broader
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context.
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Understanding these concepts is fundamental to building agents that can engage
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in complex, stateful, and context-aware conversations.
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